Cracking of hydrocarbon oils



Sept 11, 1934. N.'G.' DE linnn-IAT 1,973,471

CRA'CKING' OF HYDROCARBON OILS Filed Dec. l, 1950 j'avzace Patented Sept. 11, 1934 Y Y,

oRAcKING oF HYnRoCARBoN olLs Nicholas G. de Rachat, Chicago,`Ill., assignor to Umversal Oil Products Company, Chicago, Ill., a corporation of South Dakota Application Decemberv 1, 1930, Serial No. 499,162

3 Claims. (Cl. 196-67) This invention relates to the cracking of hydrosteam isr supplied through line 11 controlled by carbon oils, and refers particularly to an imvalve 12. proved method and means of treatment, at crack- Furnace 14 having an cuter wall 16, of suitable ing temperatures, to effect the conversion of oils refractory or insulating material may be lined; 6 into substantial quantities of more desirable if desired, with a heat resistant metallic alloy 17 6o products. or externally sheathed with any suitable material,

One specific embodiment of the invention comnot shown. An insulating and flue gas recirculatprijses introducing hydrocarbon oil into a reacing zone may be provided at 18 and inner wall 19 tion'chamber Where it impinges upon a revolving may preferably be constructed of suitable refrac- .10 disc, mounted Within said chamber. The hydrotory or heat resistant material such as rebrick, 65

carbon stream is thereby subdivided into a subcarborundurn brick or a metallic alloy. The heatstantially atomiz'ed form. Heat may be applied ing zone 20 is dened between the outer Walls externally to the walls of the chamber and may of chamber and the refractory Wall 19.

be conducted therethrough to the hydrocarbons Hot gases from combustion Zone 2 of furnace 1 175 Within the chamber to effect their conversionor may pass through duct 13 into heating zone 20 70 to maintain them at any desired temperature unof furnace 14, entering preferably near the upper der any desired pressure conditions. Cracked portion of chamber 15 and passing downwardly vapors may be Wthdrawn from the chamber to around the walls of said chamber, which may be further treatment and unvaporized residual oil heated thereby. The gases may be Withdrawn 2 0 may beA removed from the chamber to further from the lower portion of furnace 14 through duct 75 treatment'or to cooling and storage. 21 to the nue gas recirculator 22, which may As a feature ofthe present invention, combustake the Aform -of a flue gas recirculating fan or tion'products, such as-flue gas, which externally any other suitable device, and pass therefrom, heat the walls of the chamber may be introduced in part, through stack 23 to vthe atmosphere.

25 into the chamber, coming into direct contact The remaining portion may pass through duct 24 80 therein with the hydrocarbons to assist their to reheating zone 5 surrounding combustion zone conversion. Y 2 in furnace 1. The proportion of gases recircu- The salient features and the novelty of the inlated to zone vmay be controlled by dampers 25 vention will be apparent with reference to the and 26 in duct 24 and stack 23 respectively. Gases Ydrawing and the following description. thus recirculated to Zone 5 may be reheated by 85 The attached drawing illustrates diagrammaticontact with and radiation from the outer walls `cally one form which the apparatus of the present 4 of combustion zone 2 and may pass GhrOllgh dUlC' invention may assume. 27 surrounding duct 13 into zone 18 of furnace 14 Referring in detail to the drawing 1 indicates Where they may Serve G0 maintain Walls 19 at 2 a furnace having a combustion zone 2 lined with Suiciently high temperature to prevent exces- 90 refractory material such as firebrick, carborunsive radiation of heat from zone 20. Reheated dum brick or the like, the outer Walls 4 of the and recirculated flue gas frm Zone 18 may be combustion zone being preferably constructed of withdrawn through duct 28 controlled by damper some heat resistant metallic alloy such as 31 to flue SaSISCICUIaOI 29, Which may be a flue 'chrome-iron or the like althoughordinary steel gas recirculating fan or any other suitable device 95 or cast iron or any other suitable material may from which the gas is supplied through line 30 be used, if desired. A space 5 is provided surto burner 8 and therethrough to combustion rounding the outer walls of combustion zone 2, the zone 2. A utility of which will be hereinafter described. Hydrocarbon oiltobe treated may be introduced The external Walls 6 of the furnace may be conthrough line 32 controlled by valve 33 into cham- 100 structedv of. refractory material such as rebrick ber 15 and may impinge upon revolving disc 34 `or may be of common brick,lsuitab1e insulating which may be rapidly rotated by motor 35 or by material or a combination of these. If desired, any other well known means, not illustrated. The the Walls 6 may be lined with a heat resistant oil discharged upon disc 34 may be substantial- 5o metallic alloy 'l or if desired, may be sheathed ly atomized by impingement upon the rapidly ro- 105 externally With metal br insulating materiaL'not tating disc and upon leaving the disc may be shown. Burner 8 may supply combustible maprevented from striking the heated Walls of the terials to the combustion Zone, oil for example bechamber 'by regulation of the size and speed of ing introduced to the burner through line 9 conthe disc and the size of the chamber, or deflector ytrolled by valve 10 While preheated or cold air or 44 may be provided for this purpose and the im- 110 pact of the oil upon this deflector may assist in its atomization. Disc 34 may be located at any desired point in the chamber and, as here illustrated, is located in the upper portion of said chamber so that the oil discharged from line 32 may be directed, by the conical guiding member 44 disposed in the upper portion of deflector 44, to disc 34. The atomized oil may be prevented from striking chamber walls 15 by the lower portion of deiiector 44 which may also serve to prevent short circuiting of insufliciently cracked vapors and atomized oil through vapor line 40.4 The oil in a nely divided state may thus be subjected to heating by heat radiated from or conducted through the walls of chamber 15.v` j

If desired, a portion of the hot gases from zone 20 may be withdrawn through duct 36 controlled by damper 37 to iiue gas injector 38, whichmay be any suitable form of apparatus, such as, a ue gas recirculating fan capable of operating at high temperature and capable of delivering gas under relatively high pressure. The gas thus withdrawn to injector 38 may be delivered through duct 39 to the interior of chamber 15, entering the chamber at any desired point or at a plurality of points. As here shown, the hot combustion gases enter chamber 15 at its lower portion and pass upwardly through the chamber coming in direct contact with the vaporized and atomized hydrocarbons, serving to heat them and assist their conversion.

Cracked vapors with or without the admixed combustion gases, as the case may be, may be withdrawn through line 40 controlled by valve 4l and may be subjected to any desired further treatment such as for example, fractionation, followed by condensation, cooling and collection of the desired light products and return of the relatively heavy components to retreatment in the same or a separate system. Oil remaining unvaporized in chamber 15 may be withdrawn through line 42 controlled by valve 43 to storage or to further treatment, as desired, or conditions may be so controlled in chamber 15 that substantially all of the volatile constituents of the oil are vaporized, the residual products being substantially dry coke which may be collected in chamber 15 and removed after the cracking operation is-completed.

It will be understood that the apparatus of the present invention, as here described, may replace the reaction Zone of any of the present day cracking systems or, in its preferred embodiment, replaces both the reaction chamber and the heating element; for example, the oil introduced to chamber 15 may be a relatively cold raw oil withdrawn from storage or the raw oil, before being introduced to chamber 15 may be preheated to below the cracking temperature in any suitable manner, not shown, or the raw oil may be rst heated and introduced into the reaction chamber at or near the conversion temperature in Vwhich latter case the heat supplied to the hydrocarbons in the reaction chamber may be only sufficient to maintain them at substantially the same temperature, at which they are introduced into the chamber or may be sufficient to substantially increase the temperature and the rate of conversion.

Pressures employed Within chamber 15 may range from high superatmospheric pressures of several thousand pounds per square inch to substantially atmospheric or sub-atmospheric pressures. The pressures employed within the chamber may be substantially the same as those emlatmospheric pressure, said oil upon its introduction into said'zoneand ployed in other portions of the cracking system With which this apparatus may be used or may be substantially higher or substantially lower than the pressure employed in other portions of the apparatus. The temperatures maintained within the chamber may range from say '750 to 1200 F.,'more or less.

The following is given as an example of the operation of the apparatus illustrated which however, should not be construed as a limitation upon the broad concept of the invention. The raw oil charging stock to be cracked is a 36 A. P. I. gravity gas oil and after being preheated to a temperature of rabout 700 F. is discharged upon therevolving disc in the reaction chamber and thereby substantially atomized. Heat is supplied externally to the walls of the chamber in the manner already described and a temperature of about 1000 F.`is maintained in the chamber. A pressure of about 150 pounds is maintained on the pigeheating element and within the reaction chamber. The vapors are subjected to fractionation, under a substantially reduced pressure of about pounds per square inch, their heavier insufficiently converted portions being returned to the chamber together with the preheated raw oil and the lighter components of the vapors are condensed, cooled and collected. This operation may yield some 40% of motor fuel having an anti-knock value approximately equivalent to a blend of benzol and 30% straightrun Pennsylvania gasoline. In addition about 20% of heavy residual oil, suitable as charging stock for hydrogenation processes may be recovered. A

small amount of substantially dry coke is produced and the remainder of the charging stock is converted into a rich gas suitable for polymer.- ization into liquid products and particularly motor fuel of high Vanti-knock value or suitable for blending with gas of lower caloric value to Virnprove the quality of the latter.

In another typical operation a Mid-continent topped crude of about 28 A. P. I. gravity is first subjected under about 200 pounds per square inch superatmospheric pressureto a temperature of about 900 F., and is discharged at this temperature upon the revolving disc of the reaction chamber. The chamber is heated, in this case only sufiiciently to maintain the oil at about the same temperature at which it enters the chamber and the pressure within the chamber is maintained at about 200 pounds per square inch. The cracked vapors are fractionated, their heavier components being returned to the heating element for reconversion while their lighter components of the desired characteristics are subjectedto condensation, cooling and collection. Residual liquid, Withdrawn hot from the chamber is reduced to coke, in a separate low pressure zone of the same system. This operation may yieldY some 60% of motor fuel rhaving an antiknock value of approximately 50% benzol equivalent. The additional products are about 15% of pressure distillate bottoms which is highly desirable as charging stock for vapor-phase cracking, substantially dry coke and about 8% of un'- condensable gas.

, I claim as my invention:

1. A process for the conversion of hydrocarbon oils, comprising directly passing oil into a conversion Zone maintained under va cracking temperature of approximately 1000,F. and superimmediately atomizing preventing the same from contacting the walls of said zone, introducing for direct intimate contact with said atomized oil spent gases of combustion previously utilized in the external heating of said conversion zone to a cracking temperature, eiTecting vaporizaton of a portion of said oil within said zone, and removing the vaporized oil to a separate zone for further treatment.

2. A process for the conversion of hydrocarbon oil, comprising directly introducing said oil into an enlarged conversion zone, immediately impinging said oil Within said zone upon a rotating surface to effect its dispersion therein while preventing contact of the atomized oil with the walls of said zone, passing highly heated combustion gases externally and entirely about said zone to maintain the same at a conversion temperature of approximately 1000 F., thereafter introducing said gases into the interior of said zone for passage therethrough countercurrent to and in direct contact with the dispersed oil, and Withdrawing the vapors and gases from said zone.

3. A process for the conversion of hydrocarbon oil, comprising directly introducing said oil into an enlarged conversion zone maintained under high superatmospheric pressure, immediately atomizing and radially dispersing said oil upon its introduction into said zone but preventing contact of said atomized oil with the Walls of said zone, passing highly heated combustion gases externally and entirely about said zone to maintain the same under a conversion temperature of approximately 1000o F., thereafter introducing said externally passed gases into the interior of said zone for passage upwardly therethrough countercurrent tothe descending atomized oil and in direct contact therewith, removing the hydrocarbon vapors evolved Within said zone, together With the spent gases of combustion, and condensing and collecting the resultant products.

NICHOLAS Ci. DE RACHAT. 

